Anesthesia for magnetic resonance guided neurosurgery: initial experience with a new open magnetic resonance imaging system

Anesthetic challenges and outcomes for procedures in the intraoperative magnetic resonance imaging suite: A systematic review

BACKGROUND AND OBJECTIVE

Hybrid operating room suites with intraoperative magnetic resonance imaging enable image guided surgery in a fully functional operating room environment. While this environment creates challenges to anesthetic care, the effects on anesthetic adverse events and outcomes are largely unknown. This systematic scoping review aims to map the existing knowledge about anesthetic care in advanced imaging hybrid operating rooms.

METHODS

A broad-based literature search was performed using the PubMed (Medline), Embase, Cochrane Library, Web of Science, and Google Scholar databases. References published in English between January 1994 and August 2017 were included. Quality of evidence was assessed using the GRADE guidelines.

RESULTS

Forty-seven manuscripts were eligible for data collection. Adverse events were heterogeneously defined across 17 manuscripts and occurred in 0 to 100% (quality of evidence mostly very low). Monitoring difficulty was reported in 4 manuscripts of very low data quality. Interference between the magnet and the electrocardiogram was investigated in 2 manuscripts (quality of evidence low and very low, respectively). None of the reported events appeared to result in long-term patient harm. Author recommendations or a narrative review of the literature were provided in 40 manuscripts. Common safety concerns included lower equipment reliability, inaccessibility of the patient and airway, and the relative isolation of the suite (in relationship to other anesthesia care areas). Most authors also emphasized the importance of safety checklists, protocols, and provider training.

DISCUSSION

While intraoperative magnetic resonance imaging hybrid operating rooms are increasingly utilized, the existing literature does not allow estimating adverse event rates in this location. Prospective studies quantifying the effect of the environment on anesthesia outcomes are lacking. Despite this, there is a broad consensus regarding the anesthetic and safety concerns. More research is needed to inform practice standards and training requirements for this challenging environment.

Intraoperative MRI in pediatric brain tumors

Intraoperative magnetic resonance imaging (iMRI) has emerged as an important tool in guiding the surgical management of children with brain tumors. Recent advances have allowed utilization of high field strength systems, including 3-tesla MRI, resulting in diagnostic-quality scans that can be performed while the child is on the operating table. By providing information about the possible presence of residual tumor, it allows the neurosurgeon to both identify and resect any remaining tumor that is thought to be safely accessible. By fusing the newly obtained images with the surgical guidance software, the images have the added value of aiding in navigation to any residual tumor. This is important because parenchyma often shifts during surgery. It also gives the neurosurgeon insight into whether any immediate postoperative complications have occurred. If any complications have occurred, the child is already in the operating room and precious minutes lost in transport and communications are saved. In this article we review the three main approaches to an iMRI system design. We discuss the possible roles for iMRI during intraoperative planning and provide guidance to help radiologists and neurosurgeons alike in the collaborative management of these children.

Prospective Review of Safety Incidents Reported in the iMRI OT (Intraoperative Magnetic Resonance Imaging Operating Theatre)

Introduction:

The purpose of this study was to determine the types of incidents that occurred in the iMRI OT over a nineteen-month period in our institution. We aim to prevent any future avoidable incidents from happening in this potentially hazardous environment.

Methods:

This is a single centre prospective non-anonymous observational study conducted from February 2009 to September 2010 on surgeries performed in the iMRI OT. Safety incidents specific to the iMRI OT such as violation of safety protocols and equipment failures were reported as well as any other safety incidents resulting in potential or actual adverse safety outcomes. The outcomes of the incidents were included and the data analysed at the end of the study period.

Results:

Of 271 cases that were operated in the iMRI OT, 43 incidents were reported by the staff involved in the care of the patient. Of the 43 incidents, 14 incidents (32.6%) were classified as staff/personnel error and were preventable. Incidents resulted in either delayed surgery or cancellation of the surgery. There were no major adverse incidents that led to patient harm.

Conclusion:

Many of the incidents were preventable and measures have been instituted to prevent the recurrence of such incidents. Staff training, safety protocols and stringent maintenance of equipment are paramount to safe and efficient use of the iMRI operating theatre.

Clinical and economic outcomes of low-field intraoperative MRI-guided tumor resection neurosurgery

PURPOSE

To compare low-field (0.15 T) intraoperative magnetic resonance imaging (iMRI)-guided tumor resection with both conventional magnetic resonance imaging (cMRI)-guided tumor resection and high-field (1.5 T) iMRI-guided resection from the clinical and economic point of view.

MATERIALS AND METHODS

We retrospectively compared 65 iMRI patients with 65 cMRI patients in terms of hospital length of stay, repeat resection rate, repeat resection interval, complication rate, cost to the patient, cost to the hospital, and cost effectiveness. In addition, we compared our low-field results with previously published high-field results.

RESULTS

The complication rate was lower for iMRI vs. cMRI in patients presenting for their initial tumor resection (45 vs. 57 complications, P = 0.048). The iMRI repeat resection interval was longer for this cohort (20.1 vs. 6.7 months, P = 0.020). iMRI was more cost-effective than cMRI for patients who had repeat resections ($10,690/RFY vs. $76,874/RFY, P < 0.001). We found no other clinical or economic differences between iMRI- and cMRI-guided tumor resection surgeries. Overall, we did not find the advantages to low-field iMRI that have been reported for high-field iMRI.

CONCLUSION

There is no adequate justification for the widespread installation of low-field iMRI in its current development state.

Anesthesia can be safely provided for children in a high-field intraoperative magnetic resonance imaging environment

OBJECTIVES

To describe the challenges associated with providing safe anesthesia and perioperative care for children in a remote intraoperative magnetic resonance (iMR) operating room (OR) and to identify perioperative anesthesia outcomes, including adverse events related to the iMR environment.

BACKGROUND

Increasingly, children undergo neurosurgical procedures in a high-field iMR OR. We describe a 10-year experience of providing anesthesia for children in this environment with a mobile 1.5-Tesla magnet.

METHODS

A 10-year retrospective analysis was conducted of children who underwent neurosurgical procedures in a high-field mobile iMR OR. Primary outcomes related to perioperative adverse events and recovery profiles. Results were expressed as mean ± sd or median (range), as appropriate.

RESULTS

One hundred and five procedures were performed on 98 children, aged 4 months-18 years, weighing 6-112 kg. The commonest two diagnostic categories were tumor (n = 52) and seizures (n = 27). Median anesthetic time was 439 (185-710) mins. There were no significant adverse events related to the iMR environment. The mean postanesthetic care unit admission temperature was 37 ± 0.9°C and the mean modified Aldrete Score at 30 mins was 7.2 ± 0.9. Two patients experienced seizures in the immediate postoperative period, readily controlled with propofol. There was one breach of MR safety protocol, and no adverse events related to patient transport.

CONCLUSIONS

Anesthesia and perioperative care of children in an iMR setting were associated with a very low incidence of complications, despite the duration of the procedures involved. Such success depends upon a cohesive team-based approach.

Development and design of low field compact intraoperative MRI for standard operating room

OBJECTIVES

To present the development of a compact low field intraoperative MR image guidance system and its application in brain surgery.

METHODS

The PoleStar ioMRI system (Odin Medical Technologies, Israel and Medtronic, Inc. USA) was developed for use in a standard operating room. Its primary physical fixed parameters are magnetic field of 0.15 T and field of view of 20 x 16 cm. The magnet is mounted on a transportable gantry and can be positioned under the surgical table when not in use for scanning. Additional functionality includes integrated navigation, and system operation by the surgeons.

RESULTS

The PoleStar system integrates into existing operating rooms requiring only slight modification of the surgical environment. Standard instruments can be used. The system's imaging allows it to be used for the following indications: pituitary tumors, low grade gliomas (including awake surgery), high grade gliomas, intraventricular tumors, accurate navigation to small lesions such as cavernous angiomas or metastases, drainage of cysts and brain abscesses. The image quality, which is comparable to post operative diagnostic high field imaging, enables high quality resection control. More than 6,000 brain surgeries were done with the system in 50 centers in the US and Europe.

CONCLUSION

The low field intraoperative MRI system is a valuable tool in the modern operating room.

Anesthesia in the intraoperative MRI environment

Intraoperative MRI (iMRI) can be applied in several surgical settings. The incorporation of MRI technology into the operating room requires special considerations. The size and design of the operating room, including the equipment introduced into this setting, must be MR safe and allow adequate anesthesia monitoring and care. There are general restrictions and perils that may present in an operating room setting because of the MRI technology involving the monitoring equipment, anesthesia machine, and infusion devices. Incorporating the MRI technology into the operating room presents a new challenge in a transdisciplinary environment. The use of the iMRI technology has provided revolutionary tools for the new generation of medical practice.

Pituitary tumors in childhood: update of diagnosis, treatment and molecular genetics

Pituitary tumors are rare in childhood and adolescence, with a reported prevalence of up to one per 1 million children. Only 2-6% of surgically treated pituitary tumors occur in children. Although pituitary tumors in children are almost never malignant and hormonal secretion is rare, these tumors may result in significant morbidity. Tumors within the pituitary fossa are mainly of two types: craniopharyngiomas and adenomas. Craniopharyngiomas cause symptoms by compressing normal pituitary, causing hormonal deficiencies and producing mass effects on surrounding tissues and the brain; adenomas produce a variety of hormonal conditions such as hyperprolactinemia, Cushing disease and acromegaly or gigantism. Little is known about the genetic causes of sporadic lesions, which comprise the majority of pituitary tumors, but in children, more frequently than in adults, pituitary tumors may be a manifestation of genetic conditions such as multiple endocrine neoplasia type 1, Carney complex, familial isolated pituitary adenoma and McCune-Albright syndrome. The study of pituitary tumorigenesis in the context of these genetic syndromes has advanced our knowledge of the molecular basis of pituitary tumors and may lead to new therapeutic developments.

Magnetic resonance imaging anesthesia: new challenges and techniques

PURPOSE OF REVIEW

The increasing use of magnetic resonance imaging as a diagnostic modality has led to increased demand for sedation and monitoring during the procedure. This review is to acquaint the reader with the most recent developments in magnetic resonance imaging diagnostics and to describe the evolving techniques and strategies for patient management.

RECENT FINDINGS

Many centers are meeting the challenges of increasing demand by streamlining their sedation/anesthetic protocols to achieve greater efficiency. Some have enlisted the help of nursing staff who are trained to provide sedation for certain patients. Continued experience in magnetic resonance imaging anesthesia has led to a better understanding of patient needs and decreased the number of failed procedures. The scope of magnetic resonance imaging diagnostics has expanded to include urology, otolaryngology, and neonatal evaluation. Although infants and children constitute the majority of patients, many adults also require anesthesia for magnetic resonance imaging and present their own challenges.

SUMMARY

Anesthesia and sedation during magnetic resonance imaging have a unique set of constraints. However, most of the standards of modern, safe anesthetic care can be met in this environment. The growing experience at many hospitals has demonstrated that a wide range of patients can receive safe care during magnetic resonance imaging.

Detection of unanticipated intracranial hemorrhage during intraoperative magnetic resonance image-guided neurosurgery. Report of two cases

The authors report unanticipated intraoperative intracranial hemorrhaging in two pediatric neurosurgical patients. Both children were undergoing elective craniotomies with the aid of intraoperative magnetic resonance (iMR) imaging. In both cases, the ability of iMR imaging to aid in diagnosis allowed prompt and definitive treatment of potentially life-threatening complications. These cases illustrate the ability of iMR imaging to aid in differentiating unexpected and/or unexplained intraoperative events in pediatric neurosurgery.

ECG Artifacts During Intraoperative High-Field MRI Scanning

High-field magnetic resonance imaging (MRI) (1.5 T) has recently been introduced into the neurosurgical operating room for intraoperative resection control and functional neuronavigational guidance. However, long-lasting neurosurgical procedures in an operating room equipped with a high-field MRI scanner raise new challenges to the anesthesiologist. In particular, monitoring of vital signs during anesthesia requires equipment compatible with working in close vicinity to the strong magnetic field. However, even MRI-compatible electrocardiographic (ECG) monitoring interferes with electromagnetic fields, so several ECG artifacts can be observed in static and pulsed magnetic fields. As shown in this study, pulsed high-frequency fields induce characteristic field frequency-based artifacts in the ECG that can imitate malignant arrhythmia or provoke ST-segment abnormalities. The knowledge of possible and characteristic ECG artifacts during high-field MRI is therefore essential to prevent misinterpretation. Moreover, interference-free parameters such as pulse oximetry or invasive blood pressure curves are highly relevant during intraoperative MRI scans.

Anesthesia for magnetic resonance imaging

PURPOSE OF REVIEW

This review focuses on the technological principles, safety considerations, monitors and equipment, patient issues, and a general overview of the anesthetic management of both conventional and intraoperative magnetic resonance imaging based on the most recent literature.

RECENT FINDINGS

As a diagnostic imaging modality, magnetic resonance imaging remains unparalleled in its diagnostic and clinical value. The clinical applications for magnetic resonance imaging continue to evolve, and include its latest use in minimally invasive procedures as well as in the operating room. Intraoperative magnetic resonance imaging is steadily gaining acceptance for neurosurgical procedures. The safety considerations, monitor and equipment issues for intraoperative magnetic resonance imaging are similar to the conventional setting. However, they differ in their focus on anesthesia management. Most monitoring compatible with magnetic resonance imaging has been available for many years. In the USA, the newest available monitoring option during magnetic resonance imaging is for temperature. This option has been available in other countries for a number of years. A fiberoptic surface sensor provides a safe and accurate monitor of adult, pediatric, and neonatal body temperature.

SUMMARY

The magnetic resonance imaging suite is a challenging environment for the anesthesiologist, and carries inherent risks. Several factors account for this, including the remote location, the unique features of the magnetic resonance imaging scanner, and patient-related factors. Understanding the implications of the magnetic resonance imaging environment will facilitate ensuring the safety of the patient and personnel.

PoleStar N-10 Low-field Compact Intraoperative Magnetic Resonance Imaging System with Mobile Radiofrequency Shielding

The PoleStar N-10 intraoperative magnetic resonance imaging system is manufactured by Odin Medical Technologies, Yokneam, Israel, and is marketed by Medtronic Surgical Navigation Technologies, 826 Coal Creek Circle, Coal Creek Corporate Center One, Louisville, CO 80027; telephone: 720/890-3200. The cost of the PoleStar N-10 ranges from $900,000 to $1,050,000, depending on options. The price of the mobile radiofrequency shielding option is $80,000.

Anesthesia during high-field intraoperative magnetic resonance imaging experience with 80 consecutive cases

Intraoperative magnetic resonance imaging (MRI) has been used for years to update neuronavigation and for intraoperative resection control. For this purpose, low-field (0.1-0.2 T) MR scanners have been installed in the operating room, which, in contrast to machines using higher magnetic field strength, allowed the use of standard anesthetic and surgical equipment. However, these low-field MR systems provided only minor image quality and a limited battery of MR sequences, excluding functional MRI, diffusion-weighted MRI, or MR angiography and spectroscopy. Based on these advantages, a concept using high-field MRI (1.5 T) with intraoperative functional neuronavigational guidance has been developed that required adaptation of the anesthetic regimen to working in the close vicinity to the strong magnetic field. In this paper the authors present their experience with the first 80 consecutive patients who received anesthesia in a specially designed radio frequency-shielded operating room equipped with a high-field (1.5 T) MR scanner. We describe the MR-compatible anesthesia equipment used including ventilator, monitoring, and syringe pumps, which allow standard neuroanesthesia in this new and challenging environment. This equipment provides the use of total intravenous anesthesia with propofol and remifentanil allowing rapid extubation and neurologic examination following surgery. In addition, extended intraoperative monitoring including EEG monitoring required for intracranial surgery is possible. Moreover, problems and dangers related to the effects of the strong magnetic field are discussed.